Introduction of organic chemistry - MWITteppode/1_Introduction_of_organic_chemistry.pdf · 2-The human body is largely composed of organic compounds-Organic chemistry plays a central

Introduction of organic chemistry

SORACHAI SAE-LIM

1

SORACHAI SAELIM

2

-The human body is largely composed of organic compounds-Organic chemistry plays a central role in medicine, bioengineering etc.

Organic Chemistry

SORACHAI SAELIM

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ORGANIC CHEMISTRY

Organic chemistry is the study of the compounds of carbon. The compounds of carbon constitute the central chemicals of all living thing on this planet.

CHO

HO

OH

O

O

H

Gallic acid

O

OHOOH

OHCH2OH

O

HO

HO

OH

OH

SORACHAI SAELIM

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Mangifera odorata

Natural Products

SYNTHESIS

O

OH O

HO

OH

OH

O

OH O

HO

O

O

H

DPPH DPPH:H

NNO2O2N

NO2

N

N:HNO2O2N

NO2

N

DPPH DPPH:H

O

OH O

HO

OO

MF 11

+

5

Electronegativity

6

Ionic Bonds

Covalent Bonds

7

Formal charge

Ammonium ion (NH4)+

Nitrate ion (NO3)-

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A Summary of Formal Charges

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Resonance

10

11

Atomic Orbitals

-Orbital: a region in space where the probability of finding an electron is large

-Only s and p orbitals are very important in organic chemistry

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Electronic Configurations of Some Second Row Elements

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Electronic Configurations of Atoms1S2

2S2

3S2

4S2

5S2

6S2

7S2

2p6

3p6

4p6

5p6

6p6

7p6

3d10

5d10

6d10

7d10

4d10 4f14

6f14

5f14

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Bonding Molecular Orbitals

Antibonding molecular orbital

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The sharing of electrons in a covalent bond occurs by overlap of the individual atomic orbitals. Head-on overlap between energetically compatible orbitals generates sigma (s) bonds,

while sideways overlap (typically from adjacent p orbitals) generates pi (p) bonds. Example of p-bond formation between atoms "A" and "B" is shown.

Example of sigma bond formation between atoms "A" and "B" is shown.

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The Structure of Methane and Ethane: sp3

Hybridization

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Hybridization of Carbon

-Carbon may from single, double and triple bonds.

-Let’ s look at the electron configuration of ground state (lowest energy state) carbon:

6c 1s2 2s2 2p2,

2s 2px 2py 2pz

6c electron configuration of ground state = ?????

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ground state

2s

2px 2py 2pz2px 2py 2pz

Excited state

Hybridization excited

2s 2px 2py 2pz

Sp3 -Hybridization

6c

2s 2px 2py 2pz

2s

19

CH4H H H H

2s 2px 2py 2pz

Sp3 -Hybridization

Carbon-hybridization

C-H sigma bond = ….

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21

The structure of Borane hydride (BH3)

Sp2 -Hybridization

5B

22

ground state2s

2px 2py 2pz

excited

5B

2s 2px 2py 2pz

Sp2 -Hybridization

2s 2px 2py 2pz

2px 2py 2pz

Excited state

Hybridization

2s

23

H H H

Sp2 -Hybridization

BH3

Borane-hybridization

B-H sigma bond = …………………

2s 2px 2py 2pz

H

H

H

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The structure of Beryllium hydride (BeH2)

Sp -Hybridization

4Be

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The structure of Ethane (C2H6)

Hybridization of Carbon= ?????

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The structure of Ethene (C2H4)


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The structure of Ethyne (C2H2)


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Bond Lengths of Ethyne, Ethene and Ethane

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Ammonia

The bond angles are about 107o and not 109.5o

because the non-bonding electrons in effect are larger and compress the nitrogen-hydrogen bond

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Water

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Representations of Structural Formulas

SORACHAI SAELIM

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Sample Problem

Rewrite each of the following condensed structural formulas, as dash formulas as :

C

H

H

H

C

H

C

C

H

H

C

C

H

HH

HH

C

H

H

H

H

H

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Bond-Line Formulas

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SORACHAI SAELIM

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Write dash formulas for each of the following bond-line formulas:

OH

OH

OH

A.

B.

C.

D.

E.

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Three-Dimensional Formulas

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Polar Covalent Bonds

Polar covalent bonds occur when a covalent bond is formed between two atoms of differing electro negativities

•The more electronegative atom draws electron density closer to itself•The more electronegative atom develops a partial negative charge

(d-) and the less electronegative atom develops a partial positive charge (d+)

•A bond which is polarized is a dipole and has a dipole moment•The direction of the dipole can be indicated by a dipole arrow

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39

Physical Properties and Molecular Structure

-The strength of intermolecular forces (forces between molecules) determines the physical properties (i.e. melting point, boiling point and solubility) of a compound

-Stronger intermolecular forces result in high melting points and boiling points

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Physical Property

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Ion-Ion ForceDipole-Dipole Forces

Hydrogen Bonds

van der Waals Forces (London or Dispersion

Forces)

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Solubilitie

Water dissolves ionic solids by forming strong dipole-ion interactions

Generally: like dissolves like

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Generally: like dissolves like

A large alkyl group can overwhelm the ability of the polar group to solubilize a molecule in waste

44

Summary of Attractive Electric Force

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Functional Groups

-Functional group families are characterized by the presence of a certain arrangement of atoms called a functional group

-A functional group is the site of most chemical reactivity of a molecule

H

HO H

O

OH

H

H

3

1

19

58

1417

22 24

26

27

21

18

28

29 30

XCoumarinsO

O

O

OH

OH

O

HO

HO

XBenzenoides

CHO

HO

OH

O

O

H

Gallic acid

O

OHOOH

OHCH2OH

O

HO

HO

OH

OH

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C C

C C

C C

OR

OR R

H

CR H

O

Alkane

Alkene

Alkyne

Alcohol

Ether

Aldehyde

CR OH

O

CR O

O

R

CR NH2

O

NH2R

Carboxylic acid

Amide

Amine

Ester

c

O

R R1

Ketone

Functional Groups in Organic Chemistry

A functional groups is the part of a molecule where most of its chemical reactions occur.

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propene (propylene)

C C HH Ethyne (acetylene)

Alkenes are hydrocarbons that contain carbon-carbon double bond as their functional group.

Alkynes are hydrocarbons with carbon-carbon triple bond as their functional group.

C C Alkyne

C C Alkene

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CH3-CH2-OH ETHANOL

OR H Alcohol

Alcohols are organic compounds that contain the hydroxyl group (-OH) as their function group.

Alcohols are classified into three groups; primary (1o), secondary (2o), or tertiary (3o) alcohols.

This classification is also based on the degree of substitution of the carbon to which the hydroxyl group is directly attached.

OH

OH

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OR R Ether

Ethers are composed of two alkyl groups bonded to an oxygen atom. The general formula for an ether is R-O-R’ (The symbol R’ represents another alkyl group, either the same as or different from the first).

CH3-O-CH3 dimethyl ether

O CH3Cyclohexyl methyl ether

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CR H

O

Aldehyde CR R1

O

KetoneO

The carbonyl group

An aldehyde has one alkyl group and a hydrogen atom boned to the carbonyl group.

A ketone has two alkyl groups boned to the carbonyl group.

R C-H

O

R C-R

O

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CR OH

O

Carboxylic acid

CR O

O

R Ester

Carboxyl group

Carboxylic acids contain the carboxy group, -COOH, as their functional groups.

An acid derivative with an alkyl group replacing the acid proton;

CR O

O

R EsterCR OH

O

Carboxylic acid

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NH2R Amine

Amines are alkylated derivatives of ammonia.

This classification is based on the number of organic groups that are amines are alkylatedto the nitrogen atom:

Amines are classified as primary, secondary, or tertiary amines.

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CR NH2

O

Amide

Amides are acid derivatives that result from a combination of an acid with ammonia or an amine.

Proteins have the structure of long-chain, complex amides.

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Alkyl Halide

In alkyl halides, halogen (F, Cl, Br, I) replaces the hydrogen of an alkane

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Introduction of organic chemistry - MWITteppode/1_Introduction_of_organic_chemistry.pdf · 2-The human body is largely composed of organic compounds-Organic chemistry plays a central

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